AC impedance studies of SnO_2:Sc_2O_3 based CO sensor

摘要

Nanocrystalline SnO_2:Sc_2O_3 was synthesized by a two-step hydrothermal process in the presence of urea. The transient response of the SnO_2:Sc_2O_3 gas sensor to 200-1000 ppm CO was studied by AC impedance spectroscopy. Complex impedance measurement was carried out from 0.5 to 107 Hz, and the data were fitted with an equivalent circuit of two parallel circuits of a resistance and a constant phase element (CPE) in series. The sensitivity of the as-sintered samples demonstrated well linear relationship with the CO concentration. As increasing the content of Sc2O3, the operation temperature of the SnO_2:Sc_2O_3 gas sensor reaching maximum CO sensitivity reduced from 400 °C to 350 °C.